The invention relates, in general, to an arrangement for secure and sealed mounting of a head flange of an exhaust manifold to a cylinder head of an internal combustion engine.
German patent publication no. DE 44 30339 A1 describes an arrangement of this type, whereby a comparably thick head flange is provided with a number of openings in side-by-side disposition for receiving exhaust pipes. Both longitudinal edges of the head flange are provided with tongues that extend transversely. The tongues engage gaps in a clamping rail and a tension rail. Both, the clamping rail and the tension rail are fastened to the top surface of the cylinder head by several screw fasteners. After both rails are secured, the head flange can be form-fittingly joined to the clamping rail by tilting it about its central longitudinal plane and to the tension rail by moving it downwards so that the head flange rests on the top surface of the cylinder head after a seal is placed therebetween.
A number of clamping screws are rotatably supported in the tension rail. The longitudinal axes of the clamping screws extend at an angle relative to the top surface of the cylinder head. The end surfaces of the clamping screws interact with slanted surfaces on the tongues that are joined with the tension rail. As the clamping screws are tightened, the head flange can be fixed in place, whereby single projections on the clamping rail extend over the end regions of the head flange.
The particular configuration of the head flange, the clamping rail and the tension rail are difficult to manufacture. Moreover, when tensioning the clamping screws, the slanted surfaces on the tongues of the head flange subject the structure to high stress forces, when the clamping screws are tightened. In view of the present high operating temperatures which these components of the exhaust system are exposed to, the tension forces are quickly dissipated through creeping processes. As a result, leakage occurs after only a short period of time. This problem is further compounded by the spotwise attack of the clamping screws.
It would therefore be desirable and advantageous to provide an improved securement of the head flange of an exhaust manifold to a cylinder head of an internal combustion engine, to obviate prior art shortcomings and to allow easy manufacture while still being reliable in operation and not prone to leakage.